Apparatus for measuring the pitch of cylindrical and conical screws having threads of any section.



E. PERRIN. APPARATUS FOR MEASURING THE PITCH 0F CYLINDRICAL AND CONICAL SCREWS HAVING THREADS OF ANY SECTION.

APPLICATION FILED APR. 2v 19H- l,2 8 5,356. Patented Nov. 19, 1918.

4 SHEETSSHEET l- Fig.1

Emi e Parr/w E. PERRIN. APPARATUS FoR MEASURING THE PITCH 0F CYLINDRICAL AND CONICAL SCREWS HAVlNG THREADS OF ANY SECTION. APPLICATION FILED APR. 2' 19M.

1,285,356. A Patented Nov. 19, 1918.,

4 SHEETSSHEET 2.

5/777 [5 fer/7h) E. PERRIN. APPARATUS FORIMEA SURING THE PITCH 0F CYLINDRICAI. AND CONICAL SCREWS HAVING THREADS OF ANY SECTION. APPLICATION FILED APR. 2. 1917- 1 ,285,356. 7 Patented Nov. 19, 1918.

4 SHEETS-SHEET 3- E. PERRIN. APPARATUS FORIMEASURTNG THE PITCH OF CYLINDRICAL AND CONICAL SCREWS HAVING THREADS 0 Y SECTI APPLICATION APR. 2, 1 ,285,356. Patented Nov. 19,1918.

SHEET 4v 4 SHEETS- T FFT.

EMILE PERRIN, OF VANVES, FRANCE.

APPARATUS FOR MEASURING THE PITCH OF CYLINDRICAL AND CONIGAL SCREWS HAVING THREADS OF ANY SECTION.

Specification of Letters Patent.

Patented Nov. is, 1918.

Application filed April 2, 1917. Serial No. 159,383.

T 0 all whom it may concern:

Be it known that I, EMILE PERRIN, citizen of the Republic of France, residing at 104c Rue Sadi Carnot, Vanves, Seine, in the Republic of France, have invented new and useful Improvements in Apparatus for Measuring the Pitch of Cylindrical and Conical Screws Having Threads of Any Section, of which the following is a specification.

The object of the present invention is an apparatus designed to measure with great precision the pitch of cylindrical and conical screws having threads ofany section. This apparatus comprises in the first place, in the design most generally used, a base upon which slide two heads or stocks, and the screw to be measured is placed between the points of these stocks; this frame also carries two sliding uprights in which slide two supports which can be clamped at any desired height, said supports being designed to receive a rule which is provided with measuring devices.

These measuring devices comprise essen tially a sliding frame which can be made solid with the rule and carrying a fixed contact point, and a second sliding frame which can be slightly displaced upon the rule by turning a screw provided with a graduated drum, the screw being mounted in a sliding carriage which can be fixed upon the rule; the second sliding frame is provided with a movable contact which can be adjusted by means of a lever arm and carries an arm whose forked extremity presents its slit in the field of vision of a sighting telescope.

The apparatus is adjusted by clamping the sliding frame which carries the fixed contact polnt, in its standard position, then by clamping the sliding carriage, and by turning the screw mounted upon this carriage so as to bring the opposite faces of the two sliding frames to the required dis-' tance apart, such that a gage plate whose known thickness has approximately the same value as the pitch of the screw to be measured will fit between the said faces with a small amount of sliding friction. The position of the fixed and movable contact points is adjusted by means of suitable devices, and the slot of the arm which 1s solid with the movable contact point is broughtinto the center of the telescope field, after whicha sliding piece carrying a check mark is displaced so as to bring this mark in line with the slot of the arm. a

The apparatus is then readyfor use. The measurement is made as follows. Place the contact pieces upon the screw to be measured. If the above-mentioned slot is now observed to be in its original position, the measurement found is the same as the thick ness of the age plate. If the slot is seento be displace the measuring screw carried on the sliding carriage is turned so as to bring said slot into its original position, and in this case the drum of the screw shows the difference between the measurement as found and the thickness of the gage plate.

When the screw to be measured cannot be -mounted between the stocks of the preceding base or when this screw is not easily Figure 1 is a front elevation of the entire apparatus.

Fig. 2 is a detail front view on a larger scale of'the rule and the measuring devices. Figs. 3, 4 and 5 show sections made respectively according to the lines II, II-II, III-TII of Fig. 2.

Fig. 6 is a side elevation of the apparatus.

Fig. 7 shows another design for the contact points which bear upon the threads of the screws to be measured.

Figs. 8, 9, 10 and 11 show difierent forms of contacts. Fi e. 12 and 13 show respectively a front and a side elevation of another design for the base of the apparatus. Fig.

14 is a detail cross sectional view taken approximately along the line 1414 in Fig. 2.

Referring to Figs. 1 to 6, it will be observed that the apparatus comprises essentially a base A upon which can slide two stocks D and D which support the screw to be measured and which slide upon the strip V. Upon this base are also mounted two Y uprights E and E one of these being fixed while the other can be displaced along the base; these uprights are provided with grooves in which slide the twosupports F and F carrying each two grooves 00 and a:

adapted to receive the rule 0 either in the operative or inoperative position, the rule being graduated or not and carrying the measuring devices. In order to effect the simultaneous displacement of the two supports F and F in the vertical sense so as to allow of the measurement of a screw of any diameter, there are employed the two wedge-- shaped pieces G and G having similar profiles and carried by a common base plate G sliding upon the base A, the rollers 11 and H being disposedso as to bear upon these (Fig. 4) of the member T, is fixed a thin,

elongated arm 7' which is bent as shown in a vertical plane and the horizontal part of which may rest upon a stop 13- (Figs. 2 and 3) secured on the rule C. The forked outer end of this arm-j has a slot f which moves in the field of a sighting telescope M, the

latter being held by the arm h which is secured upon the frame I by the screws 17 (Figs. '2 and 4) This frame can be slightly displaced uponthe rule C by turning the differential screw P which is screwed in the sliding frame I and in a normally fixed carriage K. The screw P has a graduated cylindrical part which rotates inside a slotted reference slide Q. -The slide Q, is frictionally held in a recess of carriage K and" may be turned to cover the graduation of the screw P and prevent injury to the same. The carriage K can be clamped upon the rule C by means of the screw 2', while the spring 9 serves to take up any play which may exist.

2. A sliding frame J which can be clamped upon the rule C by means of a screw 18* and carries an upright contact piece L- for verification of the angle of the threads, said piece or gage L being frictionally and 'removably mounted and having its end shaped according to the particular pro *file of the thread to be inspected. 'The sliding frame carries-also a fixed contact point- T which canbe adjusted in the longitudi nal sense by means of the screw S and in the transverse direction of the machine 2'. e.

normally to the plane of the drawing (Figs.

1 and 2) by means of the set screws Z and Z said screws are screwed in the carriage J (Fig. 14) and bear at their ends against the part T which has a bearing against the lower edge J of carriage J so that by screwing up the screws Z and Z, the part T may be slightly tilted about the edge J whereby the testing point T is displaced in a transverse direction and brought to the exact position desired. The screws Z serve to tightly hold the point T in any adjusted position. Since this apparatus is designed for very precise measurements the contact points which are used to determine the value of the pitch are required to fulfil certain conditions of form and of position relative to each other and also to the generatrix of the screws under measurement, so that errors of actual manufacture shall have no effect upon the desired result. For instance each contact point can have two'branches, T as represented in Fig. 7 in order to bear upon the screw threads, both branches having for instance spherical ends as shown. The con tact points can have a spherical or. cylindricalform as shown in: Figs. 8, 9, 10'an'd 11.

' In Fig. 8, both pointshavea spherical form.

According to Fig. 9, they have afiat hemispherical form. In Fig. 10, they are of a cylindrical form and have rounded end-sand according to-Fig. 11, they are of a cylindrical form with flat ends.

To make a measurement, the first step is to adjust' the: apparatus. With contact points of spherical form the adjustment is.

carried'out by the use ofa grooved standard piece and agagehplate whose thickness is the sameas the pitchofthe grooves. in the standard piece The rule G is placed in thegrooves' w for the inoperative.positiong;

the sliding frame J is clamped. in'itsrnormal position and theigageplate is insertedbetween the faces a and'c of the framesrliand J. The carriage K is clamped uponthe rule and the measuringtscrew P is: turned so that the gage plate works with :a slight. friction between the faces 0 andc theuzero point" of themeasuring screw drum of screw Flying in the middle of the opening ofthe collar and the check line of the slide Q, being) placed opposite the check'line onthe slide Q. The rule C,t0getherwith the connected parts, is then transferred into =the s1ots' w and the contact points T and'T are placed in the grooves of the standard piece, '10..

which is held betweenthe centers in-D,D

the rule C and connected partsbeing then held in equilibrium by means of .the' points T, T upon the standard piece 10.. Themo-V- able point T is then adjusted vertically by the;

screw R acting-upon the lever a. The contact point T is adj usted in the longitudinal sense by the screw Sand inthe transversal direction by the screws Z and Z Adjustof the fork upon the arm 1' solid'with the movable contact T issituated at the'c'enter of the field'of the sighting telescope M.

When this is the case, the fixed contact is ment in r the longitudinal sense should-1" be1120 =carried out in such manner that the slot 7 which allow of adjusting by superposition, the adjustment is carried out in exactly the same way as the preceding, except that when the contact points are in perfect superposition, the faces 0 and 0 should be in contact.

The apparatus being adjusted in this way, each time that the faces 0 and a are separated by a given distance, if the slot lies exactly in its original check position, the distance between axes of the contact points T and T will always be the same as the distance between the faces a and 0 The contact points T and T are placed upon the screw under measurement by lowering the two supports F and F in the uprights E and E by means of the wedge shaped pieces G and G in such manner that the entire device mounted upon the rule will be supported in balanced position upon the contact points T and T; if at this time the slot f is found to be in its original position, the measurement obtained is the same as the thickness of the gage plate. If this slot is seen to be above or below the check line, the screw P is turned so as to bring the slot to correspond with the check line, and the drum of the screw will show the difference between the value of the gage late and the measurement found. It is to be observed that the gage plate is not required to have exactly the nominal value of the screw thread to be measured, and it suffices that the thickness of the plate has a value lying near the value of the screw thread, providing such thickness is exactly determined.

When the screw to be measured cannot be mounted between the two stocks of the above mentioned base, or when this screw is not easily separable, there is employed a base 13 as shown in, Figs. 12 and 18 which is mounted so as to straddle the screw, and the measuring devices remain the same as already described.

It is understood that the above described apparatus is an illustrative example, and without departing from the principles of the invention, it is possible to modify the several parts in their forms, relative dimensions and constructive details.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An apparatus for measuring screw threads comprising in combination: a fixed contact point; a contact point movable about an axis; an indicating arm connected with said movable contact point; means for placing said indicating arm in standard posi tion; means for displacing the fixed contact point with reference to the movable contact point; means for adjusting the distance between the fixed and movable contact points; means for clamping the fixed contact point; means for longitudinal dlsplacement of the movable contact point with reference to the fixed contact point; and means for measuring the displacement given to said movable contact point; substantially as described and for the purpose set forth.

2. An apparatus for measuring screw threads comprising in combination: a supporting rule; a sliding frame which is fixed upon said rule; a fixed contact point connected with this sliding frame; a sliding frame which is movable upon said supporting rule; a movable contact point pivoted upon said sliding frame; an indicat ing arm connected with this movable contact point; a checking point provided at the end of said arm; means for determining the position of said checking point; means for displacing the movable sliding frame with reference to the fixed sliding frame; a gage plate of known thickness for use with the fixed and movable sliding frames; means for displacing the fixed contact point; means for adjusting the fixed contact point in position; means for adjusting the movable contact point in position; a standard test gage of known dimensions for use with the fixed and movable contact points; clamping screws for the fixed contact point and means for measuring the displacement of the movable frame; substantially as described and for the purpose set forth.

3. An apparatus for measuring screw threads comprising in combination: a rule; supports for said rule; means for adjusting the position of said supports; a sliding frame fixed upon said rule; a piece connected with this fixed sliding frame; screws for adjusting said piece in position; a fixed contact piece carried by said piece; a sliding frame movable upon said rule; a lever pivoted upon said movable sliding frame; an adjustment screw upon said lever; a pivot carried by said lever; a movable contact articulated upon said pivot; a movable indicating arm connected with said movable contact point; a forked piece mounted at the end of said indicating arm; a supporting arm solid with the movable sliding frame and following the direction of said movable arm; a sighting telescope mounted upon said supporting arm; a sliding piece carrying a checking point provided upon said telescope; a carriage sliding upon said supporting rule; means for clamping said carriage upon the rule; a gage plate of known thickness for use with the sliding frames; means for displacing the movable sliding frame with reference to the fixed carriage; a standard testing gage I of known dimensions for use with the fixed and movable contact points; and means for measuring the displacement of the movable sliding frame with reference to the fixed carriage; substantially as described and for the purpose set forth.

Cfl

at. An apparatus for measuring. scre threads comprising incombination: abase;

stocks for supportingthe screw to be-;m ea s-. ured and movable. uponsa1d, base; slldlng uprights mountedvupon saidbase; supports whiclrslide inlsaid slidinguprights; means for displacing said supports .in-.tl1eir slides; clamping screws provided, upon. said, supports; a rule mounted upon said supports; a

slidingfraine fixed upon said rule; a piece;

connected with this, fixed. sliding frame;

screws for adjusting the position, of; said. piecewithv reference to said fixed sliding; frame; a fixed contactpiecemountedupon said piece a slidingframe movable upon said rule; a leverplvoted upon said movable slid? ing frame; aflscrew for adjustingsaid, lever in pos1tion; a plvot mountedup on, said lever, a movable contact articulated. upon said,

pivot an indicating arm connected with said movable frame; a forked piecehmounted at the endof said indicating; arm; a supporting arm sollda yw h the movable sliding-shame.

and following h i ection ofsaidimova ble arm; a sighting telescope mounted upon saidsupporting arm; a sliding piece carryinga. checking point provided upon said telescope; a carnage sliding upon the supporting rule; a screw for clamping said car-v riageupon said rule; alstandardgage plate of knownthickness for use with the sliding frames; av threadedrod mounted inthe fixed.

carriage andscrewing into the movable slidmg frame; means. for taking. up theplay or saidthreaded rod;.a standard, testing gage; of known dimensions. for, use .withithe fixed and movable contact points and. a. graduationi provided. upon said screw connecting I. the movable sliding-frame with; thefiiced Copies ,of th.is.patent .may;be obtained .for five cents each, .by; -addressi ng the ,Commissi oner ofl'atents, Weahingtmn, Di; 0; 

